In conventional water closet tanks, a flush valve is positioned near the bottom of the tank and is operable by a flush handle via chains or other mechanical linkages. As the flush valve is opened, the water within the tank drains through the flush valve opening. The water tank also includes a fill valve which often incorporates a float member such as a ball which floats on the water within the tank. Lowering of the water level within the tank lowers the ball to actuate or turn on the fill valve. When the flush valve closes and the tank is refilled, the ball then floats to its shut off position to shut off the fill valve. This system has long been used in water closets and provides for adequate flushing if there is adequate amount of water and water pressure from the tank to the bowl.
Rim flushes for one piece low profile water closets have a separate conduit leading directly from the fill valve to the rim wash ports about the upper perimeter of the bowl. The rim wash line is directly connected to the supply conduit because the low profile of the water tank relative to the bowl does not provide adequate water pressure to the rim ports at the upper perimeter of the bowl. A diverter mechanism is often provided to direct the water from the fill valve to flow through a rim wash conduit during the draining of the tank. When the tank is emptied and the flush valve closes, the diverter mechanism switches position to close off the rim wash conduit and directs water through a fill pipe (i.e. hush tube) that ends within the tank. The fill valve is actuated by the lowering of the water level within the tank. Operation of the flush handle opens the flush valve which allows draining of the water from the tank hence lowering of the water level within the tank.
Fill valves have also been devised which eliminate the use of ball cocks. These fill valves include an air pressure control chamber in which the rise in water level traps air within the chamber and causes it to be pressurized to shut off the valve mechanism in the fill valve. The main valve mechanism is opened when water in the control mechanism is drained as the water within the tank flows through the open flush valve. A fill valve of this type is described in detail in U.S. Pat. No. 4,574,826 and 4,646,779 issued to Dwight Johnson on Mar. 11, 1986 and Mar. 3, 1987, respectively. All teachings in the above mentioned patents are incorporated in this application by reference.
In tankless toilets, a flush valve handle directly operates and opens the flush valve for a certain period of time. These flush valves on tankless toilets are common in commercial and institutional settings. However, these valves need a water flow of about 25 gallons per minute to produce an adequate flush in the toilet bowl. Most residential water supply lines are incapable of supplying water at this high rate so tanks are incorporated in most residential toilets.
In low water consumption toilets which are becoming popular either by regulation or by commercial need, the amount of water within the tank is often under two gallons. Furthermore, the two gallons of water is flushed in a short six second period. This short period of time is often inadequate for the fill valve to actuate and let the water from the actuated fill valve to flow through the rim wash conduit to the rim ports and into the bowl to provide an adequate rim wash during the flush cycle.
What is needed is a tank for a toilet that provides a pressurized rim wash that simultaneously commences with the flush cycle. Furthermore, what is needed is a system which accelerates the actuation of the fill valve such that commencement of rim wash is accelerated relative to the draining of the water in the water tank so that an adequate rim wash occurs during the short flush cycle of the low water consumption toilet without the addition of separate valve mechanisms.